Place the carrots in a small saucepan and add water to cover. Bring to a boil and cook for 5 minutes or until carrots are just fork-tender. Drain. (Or you could steam the carrots instead.)

Make the cheese sauce: In a food processor or blender, combine the soaked cashews, cooked carrots, nutrional yeast, lemon juice, garlic, salt, chili powder, onion powder, cayenne (if using), and 2/3 cup water. Blend until smooth and silky, adding a splash of extra water if needed. Pour sauce into a large bowl.

Make the dip: Stir the marinara sauce, onion, and spinach into the cheese sauce until fully combined. Spoon the dip into the prepared pan and smooth the top. Sprinkly with crushed corn chips.

Bake for 25 to 30 minutes, uncovered, watching closely toward the end of the cooking time to make sure the corn chip topping doesn't burn. Garnish with sliced green onions, if desired. Serve immediately with chips or crackers.

Leftovers may be reheated in 400F oven for 10 to 20 minutes. Store in an airtight container in the refrigerator for 3-5 days.